Electric discharge device



Oct. 7, 1952 E. D. MCARTHUR ELECTRIC DISCHARGE DEVICE Filed July 14, 1949 Inventor EIT-mevr` D McArthur, by 5 w His Attorney.

Patented Oct. 7, 1952 FFICE `v ELECTRIC DISCHARGE DEVICE Elmer D. McArthur, Schenectady,` N. Y.; assigner to General Electric Co New York mpany, a, corporation of Application July 14, 1949, Serial No. 104,772

6 Claims. 1 e Y This invention relates to improvements in electrical discharge devices and, in particular, relates to improvements in high frequency electrical discharge devices useful in high frequency electrical apparatus such as described and claimed in my copending application, Serial No. 751,358, filed May 29, 1947 and entitled Electric Discharge Devices and High Frequency Systems Thereof,jnowl abandoned in favor of continuation-in-partv application Serial No. 179,854, filed August 16, 1950.

In the aforementioned application, I have described and claimed high frequency electrical systems useful as oscillators, amplifiers, reactance devices and the like and which employ grid controlled electron discharge devices as elements for controlling the energy which' is associated with a resonant circuit. It is `a general object of the invention claimed in any aforesaid application to provide an improved system characterized by a numberof advantages such as more convenient and relatively wide band frequency control, a more convenient amplitude control and structural simplicity resulting from the fact that the number of resonant circuits heretofore normally required to be associated with the discharge device may be reduced, for example, as byelimination of the resonant circuit heretofore normally associated with the cathode grid circuit of the device. v

It is a general object lof the device herein claimed to provide improvements in electron discharge devices and, in particular. to provide improvements in electron discharge devicesof their utility isfurther limitedin expandable apparatus of theabove-mention'ed character. Electron discharge devices used inradiosondes and detonating fuses must operate on small. amounts of power, since batteries are the usual'source of power for devices in these applications.

Therefore, it is anotherobject to=provide an electron discharge device for vuse .in the high frequency range Aof the electromagnetic spectrum which is quickly readied from an inactive 1 or quiescent state to a state of operation andwhich requires a minimum of power to operate.

It is alsoan object to provide an electron Adischarge devicefor use at high frequencies that is simple to construct and requires a minimum of components.

It is a further object to provide an improved generator of high frequency electromagnetic energy that is immediately readied for operation from an inactive or cold, condition in response toV a vdirecting intelligence which connects -operating Vpower to the electrode structure of the generator.` y

It is al further object to provide an improved high `frequency oscillator which is simple to construct and operate, which is light and compact, and which requires a minimum of power to opcrate. I

In general, the foregoing objects and advantages are achieved by constructing an 'electron discharge device with a directly heated lav mentary cathode in which the control grid assothe character described in my aforementioned application.

Electron discharge devices used .in certain apparatus, such as in radiosondes orin detonating fuses, operating in the high frequency range of the electromagneticspectrum, must be capable of being quickly readied for operation from an inactive or quiescent state. in responseto a controlling intelligence. Y Prior art electron disq charge devices suitable for 'thegeneration or amplification of high frequency signals, such as devices of the magnetron or klystron classes, .employ indirectly heated cathodes which take several minutes to become heated and readied for operation. Because they take such a long time to heat up, theyare not at all suited for the abovementioned purposes.` In addition 'to requiring the use of an indirectlyv heated cathode, these prior art devices are rather bulky and complicated in vstructure and operation and, -thus,

ciated with, the discharge `device is utilized as a return heater power lead for the lamentary cathode. This construction not only. eliminates a power return lead in the device by usefof the grid as the power return lead, but also results in the advantages set forth above.

The features of the invention desired to be protected are set forth in the appended claims.

vThe invention itself, together .with further ob*- J'ects and advantages thereof, may best be understood by reference to the following specication taken in connection with the single figure of the drawing wherein is shown a perspective view, in section, of an electron discharge device em-v bodying my invention. Y

. Before proceeding to explain my invention, a brief explanation as to the operationofapparatus ofv my aforementioned application is worthy of consideration. As is well known in the art, it is a common practice to employ multi-electrode electron discharge devices such as triodes having an anode, cathode and control grid as oscillators by theexpedient of providing a feedback "circuit aeia'ssa ing, the objects of the invention claimed in myA aforementioned application, Serial No. 751,358,v

are accomplished by eliminating the necessity of the cathode-grid resonant circuit and, conse-4 quently, also the necessity of feedback circuits.'

In accordance with the principlesv ofthe -nve'n--' tion of the aforementioned application, this result may be reached with an oscillator employingA a multi-electrode discharge device, such as a triode having an anode, a cathode, and a vcontrol grid, and using space charge control of current flow-in a manner similarrto: prior art oscillators, by. reducing.. .the high @frequency impedance ;be tween the grid and the cathode to: :a very; low value piteferably yas inearf to zero fasi-possible, whereby the latten two.. electrodes :are maintaned at essentially, the same f high frequency@ potential during. operation. To1.that-end, a large, byfpass capacitor may: be builtinto the discharge-tube structure @between the-grid and the cathode ,or a. -direct;,connection; mayi be made, between grid land-' xcathodeng Ire-: addition, the :nterelectrode spacingsarechosentdmeetspecifloreouirements for electron-transiti. time, which requirements" are indicated more fullyfin' the aforementionedap'- plicaton. A;

With the arrangement describedfinigthepree cedinaparaeraphit becomes possible-to generate oscillations with acircuitconsisting of a single resonantcircuit. such-asa .cavity resonatorbetweenztheanode and either the `grid or the cath- Ode. Oscll-ations maytbeinitiated as, soon asi a predetermined. minimum voltage is exceededion the anode of the device. Those oscillations; will have a ,frequency primarily-determined by the characteristics of the cavity. resonator or g other equivalent;;rcsonant; Circuit; f and: their frequency and. amplitude maygbe further controlled-bn a unidirectional bias voltage applied to the control grid. The netresultis thatfanoscillator of considerab-ly-'simplifiedconstruction-maybeprovided which hasi additionally the,l advantage.: that; it may be, caused to oscillateiin a more controllable. man: ner1throughout1a widercontinuous range offre.- quencies and amplitudes,y v l' Withireference. to .ther :invention of this: 'application. which is 'embodied4 'in n annoscillator shown in. the figure ortho drawine'...the pro- 'vision of a fllamentary cathode-cin:the'cscillator and utilizationof thexgrid: as ja heaterffpowergreturn leadjor the 'lam'entary cathode result Yin vf11rthcr. simplicity'offccmstriiction andfoperation, in; addition to. realizing-1adevice which is readied fOr-operation qui-@krinein response;toacontroiline .intelleenceland `which: recruiresla minimumsof powerfto Operator f Referring-howto thesmeleneure orfthe draw.- ing, my invention is shown- .embodiedgin anielectron dischargeydevice; i use dfrasa generator;y of electromagnetic.'oscillations.; In this insure;- ShOWn a cathode Supplying.theelectronc: cur.- rent, .e control grid 3 amianranode. The/grid is connected `t thezcathodez forgtheffhigh irequencies at :Wh-Ch; the; device is to operate-at one end by directconnection dat theothercndtya bypass capacitorf hevinesubstantially zero ref actance at the frequency of operation. With the cavity member 1, the device functions as a simple, useful and effective generator of high frequency electromagnetic oscillations when the cathode 2 is suitably heated by -a power source 8 `and a suitable source 9 of power is connected between the anode 4 and the cathode 2 and grid 3 as a high frequency uniti Referring nowto the particu-laritiesof'the gridcathode electrode structure of the device I, in order to provide an electron discharge device that can beimmediately readied for operation and also which requires a minimum of heating power, a

directly "heated cathode 2 is used. The directly `lhea'tedcathodei2 may take a variety of convenient and suitableforms. In the embodiment shown'in, theiigure, a molybdenum tungsten alloy, which has been copper plated and thence coatedJwith barium oxide may be used. This particular structure in larnentary cathodes is well knownto thosegskilledin` the artf: In /orderto heatthe cathode, it isp necessary to.connectelectric V.powery leadsrlf and,v tito eachend of thedi. reetly `lheated cathode, It .isfeasible enough to connect la PQWer lead) l` to thefilarnentarycath ode 12 atthevendzadjacent the .plug-in,V end rof the' discharge device l but supplying. Avpowerto the remote end-Q oflfthe cathode '2 presents difculties. If a power lead is brought .outatthe end l2 of the dischargedefvice l', itpres'ents'mechanical constructional complications, difiicultiesiand inconveniences, asm/ell as'. resultingin ,a serious impairment inthe electrical operation of the cir-V cuit Further,l if La lead fromjheoth'er'end of the iilarnentary cathoifeflis 'brought down through the inter-erectrddesiiacebetween the grids and cathode'" 2 or between the grida andanode 4, it seriously laffectythe, field 'configuration within thefdischarge device and, jhence, its operation. order itojvovercon'ie -gtheseA difficulties,y I have provided thatthe jcontrol'grid' 3.of the discharge device, whichnormally serves-only lacont-rol function in devices ofi this character, alsoperforms the-function-of supplying the means-'whereby the source of; electricalpowra to the cathode. may beconnected to 'remote 'end-of the directly -heatedcathode 2. 'lfhlis'the-r'emote end ofthe cath'- ode .2- is'connected-v t'o the -heater-powerlsource 8 through vmemberA 5,grid-3,memb`er yI3 andv lead l0. The end off-thecathodeZ adjacent-the fplugin end of the devicebi's'connectedftothe heater power sourcey 8 'throughz'membersxl M, 2 and Il; The direct-. -connectionaof cathode 2 andg'rld 3 by'conductiveernember 5 further@ improves the eiiiciency ,ofdevicespof the. characteriherein being described in that-member. 5- 'short-circ'uits ,the grid to the cathode directly. In devices ofthe char'f ac ter disclosed andcIaimedin my aforementioned application, it hasgbeen found: that ethegemciency and power'V output capabilities of ;the;- device are very substantially, enhanced fby;.rcduction in the impedancebetween -the grid -andi.c athode1connecl tion. It shouldbe` notedfthattheend ofthe gridcathode structure, adjacent the plug inf end/ of thedeyice :is short-circuitedfor; high-,frequencies by means of I the capacitor 6 comprisingiplates I3 and I4 and dielectric t5.fL A y The 'f yaforementioned .gr id' cathoderstructure may rbe incorporated in; the electron discharge device I- in variouswaysg; In therfigure, the cath? ode 2 isconnectedyat .one end through a spring tension I member 16 toA the cupshaped support member I f4,' :which: also -functionssas the plate -of bypassgcapaciton 6:1, 4The; grid structuretis supe lported bymeans'of rod; memberslg'l weldedto the ngrid structure; .the ends of the rods arerigidly connected to. 4flangedLoup-shaped memberf. The cathode strucjturefZ, along zw ith.,tl1ecup,- .shaped supporting memberl I 4;: is symmetrically located within the gridstructuret andthe flanged cup-shapednmernberwl.The Ifree end ofethe cathode iscondu'ctively .connected to the adjacent end of the grid by means of conductive member 5 as here'inbeforen mentioned. The cupshaped member I4 is supported withinsthe flanged member by means of a silvered,mcaqinsulator l5. The members I3 and I4 -withthe mica insulator i5 comprise a capacitor which has substantially zero impedance at the frequency-'of operation of the .device and, 'c'onscquently,osub

stantiallyshort-circuits thegridfS and-'cathode 2 at this end at4 thesefrequenciesgf lIt should .be

noted that withv this structure-,item ends for the cathode and grid are connected together by substantially zero impedance at the frequency of operation of the device.

The anode comprises a cup-shaped member 4 having a flange portion and is located preferably symmetrically with respect to the aforesaid cathode-grid structure. The member 4 is supported in place by means of vitreous member I8, which may be ceramic or any glass suitable for sealing to metal. The anode l may comprise any of a group of iron, nickel and cobalt alloys suitable for metal to glass sealing. The flanged portion of the anode member 4 is located in opposed relationship to the flange portion of the aforementioned cup-shaped member I3 with the flange portion of member I3 having a smaller diameter than the fiange of member 4 to permit insertion of the device I in cavity member l.

The support member I8 and the end wall I9 welded to the cup-shaped member I3 hermetically seal the active portions of the grid 3, cathode 2 and anode d. Conductor 20, one end of which is connected to the memberld, permits connection of the cathode power source 8 to the cathode element 2. Vitreous member 2I suitably insulates conductive member 20 and, `at the same time, makes a hermetic seal in the end wall I9. The tubulation 22 is used for the evacuation of the device I.

In order to facilitate connection of the discharge device I to a cavity structure, flange member 2l' is made with a larger radius than ange member 22. The electron discharge device I is connected to the toroidal shaped cavity member l and held in place by means of clamps 23 and spring ngers 24 of the vtoroidal member. Itis readily apparent that if the toroidal member 'I were a conductively continuous metallic member, the anode member 4 and grid member 3 would be short-circuited by this cavity. For this reason, a capacitor 25 is inserted between the upper and lower fingers 2t of the toroidal member 'l which make engagement with the upper and low- .er ange members 2 I and 22', respectively. This capacitor comprises plate members 26 and 21 and .silver mica dielectric 28. In order to strengthen .mechanically the connection between member 26 .and member 2l, suitable fasteners 29` are placed around the periphery of the toroidal member 'I .asshown These fasteners may comprise a screw member 3G and a nut member 3| joining mem bers 26 and 2l and insulated therefrom by means of fiat dielectric washers 32 and 33 and sleeve 'washers 315i.

By connection of a source 8 of heater power to aanraden offtime Qfe'teyiseconds frequency. energy may vbedestcllly.fitr-lined. from es coupling loop. 311-` cathode, said cathode iembetween .the Cathode lfaldinode 4 @S Shown' potential between cathode.andfanodebythe closingof switches 35 and Y St,` respectively, inresponseto a controlling intelligence, the device is .immediately readiedfor operation to develop high frequency electromagnetic os,cillatidns.,` for what- -ever purpose desired. By immediately is -nieant ,The high inactivity by.: mean .0f .e 1.01.1i11.i.r1sA memberfsch ,While `I haveshown escribedparticular embodiments o f. my invention, ,it will; be obvious .trathose515.1116211,inY ther art; thativarlous changes and modifications may be madewithout departing from my invention in its broader aspects and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electron discharge device for use at high frequencies comprising an anode, a grid and a cathode, said cathode including a directly energizable lamentary member, said grid including a structure symmetrically surrounding said cathode, means connecting one end of said cathode directly to the adjacent part of said grid structure, means connecting the other end of said cathode to said grid structure and forming a low impedance path between said cathode and said grid at the frequencies of operation of the discharge device whereby said cathode and grid operate essentially as a high frequency unit, and resonator structure connected between said anode and the essentially high frequency unit formed with said cathode and said grid.

2. An electron discharge device for use at high frequencies comprising an anode, a grid and a including a directly enermember, said grid includsymmetrically surrounding said cathode, means connecting one end of said cathode directly to the adjacent part of said grid structure whereby said grid may be employed as a cathode heater return, means connecting the other end of said cathode to said grid structure and forming a low impedance path between said cathode and said grid at the frequencies of operation of the discharge device, and resonator structure connected between said anode and said grid.

3. An electron discharge device for use at high frequencies comprising an anode, a grid and a. cathode, said cathode comprising a directly heated lamentary member, said grid comprising a structure symmetrically surrounding said cathode, means connecting directly one end of said cathode to the adjacent part of said grid structure and means connecting the other end of said cathode to said grid structure and forming a low impedance path between said ends of said cathode and said grid at the frequencies of operation of the discharge device.

4. An electric discharge device comprising a. cup-shaped anode member, a directly heated lamentary cathode member located within said anode member, a control grid member located between said anode and cathode members, means directly connecting adjacent ends of said cathode and grid members at the end remote from the opening of said anode member, means congizable filamentary ing a structure gridiv1 as capacitorA :having: substantially, :zero re aetancel'atl the frequenciesaofv .'operation .ofz the electromagnetic apparatusV interconnecting.. the otherl tends-'ot saldcathode i and: said. grd,means conneetlngithe plateslof fthe said .capacitory Lto a. source of. heater power .for thefcathodec,

ELMERD; MCARTHUR.y

REFERENCES-CITED The-following references-arcor frecord n--the fire' of this patenti l Y UNITED STATES PATEINIS Numbers;`

v Y NameA Datei 15 1,5443211. Hull June'30f19r25 159ltll05v Dechendtr. ,Augv'y 17;' 1926 1,259,195 Charlton etal'.A May 15.21934 2332,4282- .rAtllee-fet al.: k ,0ct'f19,;1943 

